I have a corner for movies and music. It's not ideal and I'm not under any illusions about making it such. I basically have 38 inches on each side as in the photo.

My plan is to make a small pair of 2-way speakers such as Zaph SR71 on stands that I can position for best sound.

For fuller sound and movies I thought I'd build a pair of subwoofers and use outboard class D stereo amp and crossover. However, there's not sufficient room for typical shaped boxes. (See attachment.)

Will this work? The modeled size is about 2 cu ft. I could port to rear (or front) or leave sealed. I was thinking of using the Seas L26ROY

The empty part in the middle of the model would be used for equipment and a center channel. The entire cabinet would be attached to the studs about six inches off the floor and is about 20 inches high.

My original idea was to put a single sub behind the tv with a down-firing woofer but realized how difficult was to find one that wouldn't succumb to gravity sag. Anyway, when I decided to use two small 2-way, I realized I would need to cross fairly high and stereo sub would help. My early days (about thirty years ago) built Bud Fried T-Lines and he always built in stereo.

Some other equipment will get placed behind the tv (crossover, converters, video game, etc).

My original idea was to put a single sub behind the tv with a down-firing woofer but realized how difficult was to find one that wouldn't succumb to gravity sag. Anyway, when I decided to use two small 2-way, I realized I would need to cross fairly high and stereo sub would help. My early days (about thirty years ago) built Bud Fried T-Lines and he always built in stereo.

Some other equipment will get placed behind the tv (crossover, converters, video game, etc).

But what is your opinion of the triangular boxes?

Nothing wrong with them but as Sreten points out, you are wasting space behind the TV.
You can make a single or dual slot mounted down firing sub with the speakers vertical if you are worried about cone sag.

The PPSL reference opened my eyes to a lot options I didn't realize existed. Thanks for that four letter word.

Some drivers have excessive vent noise and are not good candidates for PP.

The cones may be pointed at each other flat, or in a "V". The plenum can be made smaller if the cones are pointed at each other, allowing more cabinet volume than a PP.

Using Hornresp and modeling the slot plenum as a stubby horn you can get an idea if the plenum resonance will be a problem for the desired crossover point you choose.
The example below could be elevated and down firing, or the "V" could be open to fire forward.